Many search engine services, such as Google and Overture, provide for searching for information that is accessible via the Internet. These search engine services allow users to search for web pages and other Internet-accessible resources that may be of interest to users. After a user submits a search request that includes search terms, the search engine service identifies web pages that may be related to those search terms.
To quickly identify related web pages, the search engine services may maintain a mapping of keywords to web pages. This mapping may be generated by “crawling” the web (i.e., the World Wide Web) to identify the keywords of each web page. To crawl the web, a search engine service may use a list of root web pages to identify all web pages that are accessible through those root web pages. The keywords of any particular web page can be identified using various well-known information retrieval techniques, such as identifying the words of a headline, the words supplied in the metadata of the web page, the words that are highlighted, and so on. Some search engine services can even search information sources that are not accessible via the Internet. For example, a book publisher may make the content of its books available to a search engine service. The search engine may generate a mapping between the keywords and books.
When a search engine service receives a search request that includes one or more search terms, it uses its mapping to identify those information sources (e.g., web pages or books) whose keywords most closely match the search terms. The collection of information sources that most closely matches the search terms is referred to as the “search result.” The search engine service then ranks the information sources of the search result based on the closeness of each match, web page popularity (e.g., Google's page ranking), and so on. The search engine service then displays to the user links to those information sources in an order that is based on their rankings.
Some search engine services do not charge a fee to the providers of web pages for including links to their web pages in search results. Rather, the search engine services obtain revenue by placing advertisements along with search results. These paid-for advertisements are commonly referred to as “sponsored links,” “sponsored matches,” or “paid-for search results.”
An advertiser who wants to place an advertisement along with certain search results provides a search engine service with a prospective advertising bid. Typical prospective advertising bids include (1) one or more search terms, (2) a bid amount, and (3) an advertising message. When a search request is received from a user, the search engine service identifies one or more of the already-received prospective advertising bids meeting certain criteria, such as those having the highest bid amounts among those including matching search terms, or those having the highest expected value among those including matching search terms. The engine service returns a search result in response to the received search request that includes the advertising messages of each of the identified prospective advertising bids. This search result, together with the included advertising messages, is displayed to the user.
Bidding on search result advertising opportunities using prospective advertising bids have a number of disadvantages for advertisers. First, it often requires a great deal of ongoing effort for an advertiser to select search terms and optimize its bids for these search terms. Second, there tends to be a practical limit to the number of search terms for which an advertiser can maintain prospective advertising bids. As a result, an advertiser often must forgo a large group of search terms, even though (1) the advertiser fully expects them to be included in one or more search queries received by a typical search engine and (2) the advertiser could benefit from bidding on them, because the overhead of bidding on them is too high relative to the likely benefit. Third, to effectively use prospective advertising bids, an advertiser must to be able to anticipate search terms that will be included in future search queries. If search engines receive a large number of queries including unexpected search terms, such as search terms relating to a news story or new product announcement, it can take an advertiser a substantial period of time to respond by submitting prospective advertising bids for these search terms, causing the advertiser to miss out on a substantial number of advertising opportunities. Fourth, prospective advertising bids typically do a poor job of differentiating between individual advertising opportunities in which the query contains the same search term, such as search requests received from different individual users, some of whom are good prospects and other of whom are poor prospects; search requests received on different days or at different times; search requests specifying different combinations of search terms; search requests including particular query constructs, such as Boolean operators; search requests received at a time when an advertised item is out of stock; etc.
An approach to seeking search result advertising opportunities that overcame some or all of these disadvantages of prospective advertising bids would have significant utility.